The present invention concerns novel reactive polysiloxanes and a method for their manufacture. More specifically, the present invention concerns polysiloxanes of mainly SiO.sub.4/2 polysiloxane units which have highly reactive halogen atoms bonded to silicon and a method for their manufacture.
Polysiloxanes comprised of monofunctional siloxane units and tetrafunctional siloxane units have been known and used in many fields. Common manufacturing methods involve hydrolysis of water-soluble silicate salts such as water glass, etc. under acidic conditions, with termination of the polymerization using trimethylchlorosilane, etc. (U.S. Pat. Nos. 2,676,182 and 2,814,601); cohydrolysis of alkyl silicates and hydrolyzable trialkylsilane mixtures (U.S. Pat. No. 2,857,356; Japanese Kokai Patent Application No. Hei 3{1991}-139526); and addition of alkyl silicates or their partial hydrolyzates to trialkylsilane hydrolyzates (Japanese Kokai Patent Application No. Sho 61{1986}-195129). These methods include hydrolysis processes under acidic conditions, and imparting functional groups unstable to water (e.g., Si-halogen group) to the polysiloxanes are very difficult. There have not been any reports on reactive polysiloxanes comprised of monofunctional units and tetrafunctional units which easily undergo nucleophilic substitution.
It is a task of the present invention to provide novel and useful reactive polysiloxanes comprised of monofunctional units and tetrafunctional units which easily undergo nucleophilic substitution, especially to provide Si- functional polysiloxanes.
The polysiloxanes of the present invention are novel compounds useful for the manufacture of branched polysiloxanes of mainly polysiloxane units of SiO.sub.4/2 and diorganopolysiloxane unit branches, as the starting materials for silicone elastomers. They are also useful as additives for improving flow characteristics of silicone fluids.